This filter primitive performs the combination of two input images pixel-wise in image space using one of the Porter-Duff compositing operations: over, in, atop, out, xor and lighter. Additionally, a component-wise arithmetic operation (with the result clamped between [0..1]) can be applied.

The arithmetic operation is useful for combining the output from the <feDiffuseLighting> and <feSpecularLighting> filters with texture data. If the arithmetic operation is chosen, each result pixel is computed using the following formula:

result = k1*i1*i2 + k2*i1 + k3*i2 + k4

where:

i1 and i2 indicate the corresponding pixel channel values of the input image, which map to in and in2 respectively

k1, k2, k3 and k4 indicate the values of the attributes with the same name